Backpack



FIG. 1 is a front view of a backpack, showing our new design;

FIG. 2 is a back side view thereof;

FIG. 3 is a right side view thereof, the left side being a mirror image;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a perspective view thereof; and,

FIG. 7 is a reference view thereof; showing a perspective view of the backpack with open flaps.

The broken lines show portions of the backpack that forms no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 